How to solve this issue?

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Hi all,
i got this error "Uncaught TypeError: Cannot read property '0' of null" in console while click the link.

C#

var c = parseInt(e.attr("class").match(/rating\d+/)[0].replace('rating', ''));

this is the line which shows the error.

Thanks,
Sampath

Posted 14-May-14 3:13am

Sam Path

Updated 14-May-14 3:17am

CHill60

v3

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joshrduncan2012 14-May-14 9:41am

Ok, so what is your question?

Sergey Alexandrovich Kryukov 14-May-14 11:04am

Is it Javascript? If it is, why all the other tags in the question? When you add unrelated tags, it only reduces you chance to have anyone who would look at your question and answer.

As to your question: rewrite it in several different lines, with intermediate variables. Then, under the debugger, examine each step. Find out where you expected non-null but get null. What is e? it could be null, or e.attr("class") can be null, and so on...

—SA

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Andreas Gieriet · Answer 1 · 2014-05-14T06:15:00

Never chain anything unless you know for sure the intermediate objects are defined.
I.e. x.y[z].f() is far too offensive programming.

In your case:
- e.attr("class") may not point to any object
- ...match(...) may not match, thus the number of matches is 0
- ...[0] may be out of range (see above)

Split it into separate chunks, store in a variable each and check if the returned object is defined before going on to the next part.

Cheers
Andi